A known three-roll rolling mill includes three reduction rolls radially arranged at angular intervals of 120 degrees in a vertical plane and adapted to be rotated to roll a metal strip from three peripheral sides so that the metal strip is formed into a metal bar, wire rod, or the like. Each reduction roll is conventionally supported at its opposite ends by a pair of bearings.
For purposes of controlling the rolling mill, it is generally known to equip the mill with load cells for detecting the rolling force. For mounting a load cell, it is preferable to utilize a space, for example, between each bearing and a mill housing. However, when load cells are installed for only one of the three reduction rolls, the problem is that the overall rigidity of a support system for the one reduction roll (which consists of the load cells, a roll holder, and a support frame) becomes different from the overall rigidity of a support system for each of the two other reduction rolls with no load cell installed therefor (which comprises a roll holder and a support frame). As such , no uniform elastic displacement is achievable with respect to individual reduction rolls during rolling operation, product quality being thus adversely affected.
In order to eliminate such inconvenience, it may be conceivable to provide load cells with respect to all the reduction rolls. However, this naturally involves increased cost.
Furthermore, it may sometimes be impracticable to provide load cells for all the reduction rolls because of limited space availability.